P51D vs Spitfire MkXIV (14)

[fd ski]

Tony oh Tony,
would you kindly please stop clouding the discussion with facts !!!

 

As for perking of Spit XIV, how convinient that most of those calling for it are 109G10/P51D/La7 drivers protecting thier dominance...  

Verm, Spitfire LF IX  would be even more wreck to the arena that XIV i think...
 

[Zigrat]

imo lf.ix should be added unperked with 10 eny.  xiv added as perk 20 perk point range.

[Nashwan]

The ADFU comparison figures are far to general to draw exact figures from them:

38. From 0 - 5,000 ft and 15,000 - 20,000 ft., the Spitfire XIV is only 20 m.p.h. faster; at all other heights it is up to 60 m.p.h. faster than the Fw 190 (BMW.801D). It is estimated to have about the same maximum speed as the new Fw 190 (DB.603) at all heights.

(109G)
44. The Spitfire XIV is 40 m.p.h. faster at all heights except 16,000 ft. where it is only 10 mph faster.

And from figures like that you want to guestimate speeds of aircraft down to a few mph?

 

There doesnīt exist a 190A in english reports which did more than 340mph near ground afaik. So when the Spit14 did more than 355-360mph, why didnīt they mention this 190A in reports?

340 for a 190A. The AFDU report says:

38. From 0 - 5,000 ft and 15,000 - 20,000 ft., the Spitfire XIV is only 20 m.p.h. faster; at all other heights it is up to 60 m.p.h. faster than the Fw 190 (BMW.801D). It is estimated to have about the same maximum speed as the new Fw 190 (DB.603) at all heights.

Which would make the Spit XIV around 360 at sea level. The actual performance trials showed a speed of 363 at sea level, which I think fits pretty nicely with 20mph faster than a 190A.

 

Well, first i have to say: What is a report worth where aircrafts are compared without mentioning the exact weight, aircraft condition, power setting etc.??? NOTHING!

I agree. So why do you wish to take such a report (the AFDU comparison) and value it more highly than full performance evaluations?

Nowhere in the AFDU report does it give aircraft speeds to a greater than 5mph accuracy:
 

At all heights the Spitfire XIV is 30-35 mph faster in level flight
From 0 - 10,000 feet the Tempest V is 20 mph. faster than the Spitfire XIV. There is then little to choose until 22,000 feet, when the Spitfire XIV becomes 30-40 mph. faster
From 0 - 5,000 ft and 15,000 - 20,000 ft., the Spitfire XIV is only 20 m.p.h. faster; at all other heights it is up to 60 m.p.h. faster than the Fw 190
The Spitfire XIV is 40 m.p.h. faster at all heights except 16,000 ft. where it is only 10 mph faster.

They are rounding the figures to at best 5mph, possibly even 10mph.
So a 360 mph Spit XIV is easily a 363 mph (they probably didn't even do full performance trials for all aircraft at the AFDU, that was the A&AEE's job)
The "30 mph faster than a Spit IX" can easily be 27mph faster than a Spit IX, which would put the Spit IX at 336mph at sea level, coincidentally exactly the figure given by the A&AEE during their tests of the Spit IX.

 

We donīt know how much power the Spit had at sealevel, BUT we know it from the 2nd gear, around 1800hp, right?
The difference in climbrate is 5100-3600 = 1500ft/min.
To lift 8400lb with another 1500ft/min, you need ~450hp.
Itīs easy to see that the Spit must have had
more than 2200hp near ground.

I'll admit I don't understand this too well, and I may be very wrong, but I don't believe it had 2200hp.
I have never seen a figure of more than 2050 hp quoted for the Griffon 65, unless it's running on higher octane fuel.
I believe the actual figure was 2035hp, which is usually rounded to 2050.
I do know that the same Griffon 65 could produce 2350hp, running at 25lb boost. In the tests where it achieved 363mph at sea level, and 5110 ft/min at low level, it was running at 18lb boost. That is clearly stated in the test report.
So far we have 200-250 hp extra accounted for, which just leaves around 200 hp.
But doesn't full superchrager gear ratio take more power? Don't you have to work harder to compress the air at higher alts to maintain that 18lb boost? Would the FS gear require a lot more HP than MS geat, which is all you needed at lower alts?

[mw]

Yikes, got to pull on my hip boots, the crap is getting deep in here!  

First the AFDU tests were done at the behest of Fighter Command and later ADGB for the pilots that had to fly the planes.  It gave some context to how the RAF planes would fly as compared to their contemporaries.  What the pilots needed to know was things such as; is my plane faster, better climbing, better turning, etc.  Since the report in question is number 117, I figure Fighter Command pilots got something out of them or they wouldn't have kept doing them.  If nothing more it gave the RAF pilots flying the Spit XIV confidence to "mix it" with any 190's they should encounter  

There's some umm... creative math being misapplied here, lol!  Lets just look at the speed comparisons on the AFDU report, focusing on Sea level speeds.  

Spit XIV vrs Spit LF IX  "At all heights the Spitfire XIV is 30-35 mph faster in level flight."  From A&AEE LF IX did 336 Spit XIV 363.  Close enough Ok checks out. (446 vrs 407 at alt)

Tempest V vrs Spit XIV: "From 0 - 10,000 feet the Tempest V is 20 mph faster."  I have two reports on Tempest V series I sea level speed.  376 and 380 mph for the Tempest V versus 363 for the SPit XIV.  Checks out.

FW 190A4 vrs Spit XIV: "From 0 - 5,000 ft and 15,000 - 20,000 ft., the Spitfire XIV is only 20 m.p.h. faster."  340 mph for the 190 according to above account vrs 363 for the Spit XIV.  Ok close enough.

Adds up to me.  

In addition if you read the first para. of the AFDU report it says " It was discovered that this aircraft (RB.141) was not representative of production aircraft for Squadrons, and Spitfire XIV No. RB.179 was made available and delivered on 25.2.44.  

As far as distorting what Quill said, hehe, sheesh... The planes that A&AEE wrote reports on were located at Boscombe Down and tested by their pilots.  Heck I've got pics of all the Spit XIV's that were tested AT Boscombe Down, JF319 among them.   A&AEE didn't feel they had to test EVERY mod as they had a degree of trust in Supermarine.  However, if you look at the the Spit IX A&AEE test of a Spit IX running at +25 boost one is likely to conclude A&AEE felt a  need to check the results of the manufacturer and indeed concluded "The agreement between the Rolls-Royce and A.& A.E.E. performance figures is quite reasonable though the speeds particularly are much lower than those obtained by Messrs. Bickers Armstrong on the other aircraft."  If I were doing the FM I'd use the A&AEE data.  It's what the Ministy of Supply bought after all.  I too am suspicious of manufacturer's data and like others figured that 190 chart to be "optimistic"  and without sufficient supporting documentation.

hmmm I'm not sure, but is the implication that the AFDU Spit XIV was operating at +25 boost?  Hey, if that were so those comparisons would have been way off as a Spit XIV at +25 boost was pushing 400 mph at sea level.  Be very glad no one is asking for THAT monster here.  They were operational too  


edit:  LOL Nashwan, you type faster  

[ 11-21-2001: Message edited by: mw ]

[R4M]

Originally posted by Tony Williams:


From my next book (with Emmanuel Gustin):

"The kill probability of a 2.5 second burst from a quartet of Hispano Mk II was quoted as 80% at 275 m and 60% at 365 m."

You can work out what it would be with two cannon.  The .50s needed LOTS more hits to kill a plane, as attested by the number of German fighters which returned safely to base despite being damaged in action against US bomber formations.

Comparison of the 20mm SAPI with the .50 M8 API is instructive.  The M8 had a hard core with about 1 gram of incendiary material in the tip.  The SAPI was a cannon shell with a hard cap.  It could penetrate about the same as the M8 (15-20mm armour) but contained 11 grams of incendiary material - yep, eleven times as much.  The 20mm HEI contained the same amount of Pentolite or Tetryl.  In destructive ability it was in a different league from the .50

Tony I dont say the spit Hispanos were better/worse when hitting. I say that it was easier to hit with the 50 cals on the P51 than with the Hispanos in the Spitfire.

Simply said, the P51 puts more lead in the air per second, and can put it for much more time than the Spitfire.Given the very low hit-rate on an average pilot gunnery in WWII the P51 weapons still seem more effective for me than the Hispanos.

IF a hit was achieved, of course, cannons were much better; but I still think that it was better to have a weapon easier to hit with,at the cost of a lower hitting power. Main problem for an average pilot in AtA fights was to hit, and the american birds allowed for much more forgiving fire practices (high-deflection low-probability shoots, long range shooting, etc) than the spitfires.

Of course then you take Marseilles, who with one 20mm mauser and two 7.9mm MGs caused real havoc   but I'm talking about the average pilot here  

[Vermillion]

Ahhh Funked, you know I'm just messing with you.  

Hell, don't forget that I was the first to coin the term "Nancy Boy Spit Dweebs".  

That was my signature for a Loooooong time, and was I believe famous in AW, AH, and WB's all at the same time. heheheheheehheheh.